When vehicles are parked outdoors overnight during cold ambient conditions, condensation may occur on the exterior surfaces of a windshield and other cabin windows. Condensation on cabin windows may be due to thermal inertia of the cabin glass surfaces, which lag behind ambient temperatures and therefore, may be cooler than ambient dew point. If ambient temperature is below freezing, the condensed water droplets on the windows may freeze to form frost on the windows. Condensed water droplets, and frost, accumulated on the windshield and other windows may be cleared by starting the engine and blowing hot air onto the interior glass surfaces of the vehicle. Frost may also be cleared by spraying detergents onto the exterior surface of the windshield while simultaneously warming the interior surface of the windshield. However, all these methods are performed after an engine start and therefore may increase fuel consumption. Further, the driver may have to plan for additional time to clear and scrape the windows.
The inventors herein have recognized the above issues and identified an approach to at least partly address the issues. In one example approach, a method for preventing condensation on the windows of a shut down and parked vehicle is provided. The method comprises, following vehicle shut down and when a temperature of a windshield is lower than ambient dew point, transferring heat to a windshield of the vehicle via a coolant if a powertrain temperature is higher than the windshield temperature, and transferring heat from ambient air to the windshield via the coolant if the powertrain temperature is lower than the windshield temperature, and ambient temperature is higher than the windshield temperature.
For example, when a vehicle is parked outdoors and shut down with an engine at rest, a controller may be activated by a timer at regular intervals to monitor ambient temperature, ambient dew point, cabin temperature, and a temperature of a powertrain. A temperature of a windshield and other windows of the vehicle may be inferred from ambient temperature and cabin temperature. If ambient temperature is increasing and windshield temperature is below ambient dew point, the controller may initiate a procedure to warm the windshield. An electric coolant pump and an electric thermostat may be activated to allow coolant circulation. If the powertrain temperature is higher than the windshield temperature, the coolant may be circulated across the powertrain to absorb heat from the powertrain. If the powertrain is cooler than the windshield temperature, the coolant may extract heat from ambient air when the ambient temperature is higher than the windshield temperature. Herein, the coolant may be circulated through a radiator while operating an electric radiator fan to draw ambient air across the radiator, thus enabling the coolant within the radiator to absorb heat from ambient air. Finally, the warm coolant may be circulated through a heater core and an electric blower fan may be activated to direct hot air onto the interior surfaces of the windshield and other windows.
In this way, condensation, and frost, may be prevented from forming on the exterior surfaces of a windshield and other windows of a vehicle with an engine at rest. By monitoring the windshield temperature along with ambient conditions at regular intervals following vehicle shut down, the windshield and other windows may be maintained at a temperature above ambient dew point. The coolant may be circulated by activating the electric coolant pump and the electric thermostat, and heat may be transferred to or from the coolant by actuating the electric radiator fan and the electric blower fan. An on-board battery may be used to energize all the components that enable circulation of the coolant and heat transfer to and from the coolant thus avoiding an engine start for the purpose of clearing condensation. Overall, by preventing the formation of condensation, fuel consumption may be reduced and a savings in time may be realized.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.